Method of making alkaline earth metal naphthenates



'nited States METHOD OF MAKING ALKALINE EARTH METAL NAPHTI-IENATES No Drawing. Application January 12, 1955, Serial No. 481,485

9 Claims. (Cl. 260-514) This invention relates generally to organic salts, and more particularly to salts of naphthenic acids. Still more particularly, it relates to an improved method of making alkaline earth metal naphthenates.

The fusion process is one of the most common methods of preparing alkaline earth metal salts of fatty and naphthenic acids. In this process, it is conventional to heat naphthenic acids and then to neutralize the acid by the gradual addition of the stoichiometric amount of the alkaline earth metal compound, usually calcium hydroxide. Although this process is straightforward and readily carried out, it suffers from at least one disadvantage. The acid number of the resulting calcium naphthenate reaction product is quite high, usually between 20 and 55. By conducting the reaction at a lower temperature and by adding calcium hydroxide at a slower rate, this high acid number could be reduced somewhat. Under these conditions, however, the reaction time is unduly prolonged and the acid number is still not as low as it should be.

Accordingly, it is an object of this invention to present a process of preparing alkaline earth metal naphthenates which does not suffer from the above described disadvantages. It is a further object to present a process of preparing alkaline earth metal naphthenates having very low acid numbers. It is a still further object to present a process of making alkaline earth metal naphthenates having low acid numbers, which process may be carried out in a relatively short period of time.

These objects are accomplished in a surprisingly simple and effective manner. A mixture of a naphthenic acid and an inorganic alkaline earth metal compound is heated to a temperature in the range of about 260 F. to about 305 F. in contact with water, whereupon, in a relatively short period of reaction time, there will be formed an alkaline earth metal naphthenate having an acid value lower than 5.

The naphthenic acids to be used in the present process are an item of commerce. They may be obtained in varying degrees of purity. The main impurity generally comprises mineral oil. It has been found that the mineral oil impurity, rather than detracting from the present process, actually expedites it. Although naphthenic acids may be used in the present process in a pure form, it is preferred that mineral oil be present in suitable amounts. The amount of mineral oil is not critical, since the process functions very well without any mineral oil at all, yet 3-35% mineral oil is often desirable. This is particularly true where the alkaline earth metal naphthenate is to be utilized in those formulations which call for mineral oil. Exemplary of such formulations are the various recipes for asphalt tile. If the calcium or alkaline earth metal naphthenate is to be used in an asphalt tile, it is expedient to add to the original naphthenic acids sufficient mineral oil to make up that amount called for in the asphalt tile formula. Thus, upon the completion' of the salt-forming reaction, the alkaline earth metal naphthenate admixed with the proper amount of to temperature.

2 mineral oil is ready to be used directly in asphalt tile formulations.

The alkaline earth metal compound to be used in the present process is not critical. Generally, the alkaline earth metal hydroxide is preferred, and calcium hydroxide is the preferred member. Calcium and barium oxide may be used if desired, but they are a little more ex,- pensive than the hydroxide. Salts such as the carbonate may be used; however, reaction time is a little longer than when the hydroxide is used. The alkaline earth metal compound, therefore, may be the hydroxide, the oxide, the salt, or mixtures thereof.

The requisite amount of naphthenic acid in mineral oil, if desired, is admixed with an amount of the inorganic alkaline earth metal compound substantially stoichiometric to the naphthenic acid. The mixture is then heated to a temperature above the boiling point of water. Generally speaking, this temperature will be in the range of about 260-305 F. Temperatures lower than about 260 F. caused an impractical increase in reaction time, and in any case, do not allow the reaction to go to completion. Temperatures higher than about 305 F. cause an excessive exothermic reaction.

Water, preferably hot, is added to the heated mixture. The exact amount of water to be added is not critical, but it is preferred that sufficient water be present to cover the reaction mass. A lesser amount of water than this will enhance the reaction to some extent, but will not produce the unexpected results obtained when adequate water is added.

One of the surprising and unexpected features of the present invention is that when the hot water is added to the mixture, which has been heated above the boiling point of water, the water does not immediately flash oif. Instead, the water will remain in contact with the heated mixture for a period of time that generally ranges between about 1-8 minutes. Since the water eventually boils off, it is preferred to add the water in several batches. In this way, water may be kept in Contact with the heated mixture of naphthenic acids and alkaline earth metal compound during the entire reaction period, which may be, for example, about one-half hour. Each addition of water may consist of hot water in an amount equal to about half the weight of the heated reaction mixture to which the water is added. For example, if the heated mixture weighs parts by weight, each addition of water may preferably be about 50 parts by weight. The hot water is simply poured into the heated mixture during agitation. Several minutes later, when the water has about boiled off, another addition, consisting of another 50 parts by weight of water, may be added, and so on until the reaction is complete.

On each addition of water, the temperature of the reaction mass will drop somewhat. For this reason, it is advisable to have an adequate source of heat by means of which the reaction mass may be swiftly brought back Although cold water may be added, hot water is preferred, since there is less heat fluctuation in the reaction mass during the course of reaction.

Another advantage of the present process is that any impurities existing in the reactants may be readily re moved by the water. For example, after a water addition has been made and before the water from that addition has completely boiled off, it may be poured off, decanted, or otherwise removed from the heated reaction mixture. The second addition of water is then made, and

so on.

Although it is preferred that several water additions be made during the course of the reaction, such is not necessary. Instead, the reaction mixture may be maintained within the disclosed temperature range for a longer period of time, as for example about 3 hours, and then a single water addition be made in order to complete the reaction. This latter method will produce an alkaline earth metal naphthenate having an acid number less than about 5, although it does require a longer period of time'than the previously described method. In any case, either of the methods represents a great improvement over prior methods of salt formation, since those prior methods consume an even greater amount of time.

Alternate procedures are available. For example, it is feasible to heat up the naphthenic acids, with or without mineral oil, in the presence of water until a temperature in the range of about 260-305 F. is reached, at which time the inorganic alkaline earth metal compound may be added. The rate of heating should be such in this latter case that there is still water present when the desired temperature range is reached, at which time the alkaline earth metal compound is added.

The following examples illustrate several embodiments of the invention.

Example I A mixture of a naphthenic acid and mineral oil weighing 960 parts by weight, containing 22% mineral oil and wherein the naphthenic acid has an acid number of 185, was admixed with 173 parts by weight powdered dry calcium hydroxide containing 92.4% Ca(OH) The mixture was heated to a temperature of 302 F. and maintained at that temperature for 3 hours. On cooling, the acid number was 52.

This example illustrates prior methods of preparing calcium naphthenates.

Example II A mixture of a naphthenic acid and mineral oil amounting to 960 parts by weight, containing 22% mineral oil and wherein the naphthenic acid has an acid number of 185, was admixed with 173 parts by weight powdered dry calcium hydroxide containing 92.4% Ca(OH) The mixture was heated to about 290 F., whereupon there was added boiling water in an amount of about 500 parts by weight.

Over a period of one hour, 12 additions of water were made, each of about 500 parts by weight. At the end of one hour, the reaction product was removed and oven dried. The calcium naphthenate had an acid number of 2.5.

When a similar reaction is carried out with stoichiometric quantities of barium hydroxide and with calcium carbonate, a similar product resulted save that the reaction was carried out over a period of 1% hours.

Example III A mixture of 670 parts by weight Sunaptic acid, grade A (naphthenic acid-mineral oil mixture of acid number 170-180 and viscosity, Sayboldt Universal/210 F. of 120-140 seconds), 150 parts by weight mineral oil, aniline point 98 C., and 105 parts by weight powdered dry 92.4% calcium hydroxide was heated to 302 F. and 6 additions of boiling water over a period of /2 hour were made. On oven drying, the calcium naphthenate product had an acid number of 1.7.

Example IV A mixture of 606 parts by weight Sunaptic acid, grade B (naphthenic acid-mineral oil mixture of acid number 145-155 and viscosity, Sayboldt Universal/210 F. of 200-225 seconds), 110 parts by weight mineral oil, and 153 parts by weight calcium hydroxide was heated to 302 F. and maintained at that temperature for 3 /2 hours. At the end of that period, about 400 parts by weight of boiling water was added. A violent reaction ensued for a period of time of about one minute.

The product was oven dried, yielding a calcium naphthenate having an acid number of 1.5.

Example V A mixture of 742.5 parts by weight Sunaptic acid, grade C (naphthenic acid-mineral oil mixture of acid number -130 and viscosity, Sayboldt Universal/ 210 F. of 400-450 seconds), 119.4parts by weight mineral oil, and 133.5 parts by weight calcium hydroxide was heated to a temperature of 270 F; Over a period of two hours, 4 additions of water were made, each of about 500 parts by weight.

On oven drying, the calcium naphthenate had an acid number of 2.6.

I claim:

1. The method ofmaking an alkaline earth metal naphthenate which comprises heating a mixture of a naphthenic acid and an inorganic alkaline earth metal compound to a temperature in the range of about 260 F. to about 305 F. in contact with water'in amount sufficient to cover the reaction mass.

2. The method according to claim 1 wherein said alkaline earth metal compound comprises calcium hydroxide.

3. The method of making an alkaline earth metal naphthenate which comprises heating a mixture of a naphthenic acid and an inorganic alkaline earth metal compound to a temperature in the range of about 260 F. to about 305 F. and adding water to said heated mixture in amount suflicient to cover the reaction mass, whereby there is formed alkaline earth metal naphthenates having an acid number lower than 5.

4. The method according to claim 3 wherein said water addition is accomplished stepwise.

5. The method according to claim 3 wherein said water is added hot and in an amount equal to approximately half the weight of said naphthenic acid and said inorganic alkaline earth metal compound.

6. The method according to claim 3 wherein said inorganic alkaline earth metal compound is calcium hydroxide.

7. The method of making an alkaline earth metal naphthenate which comprises heating a mixture of a naphthenic acid, mineral oil, and an inorganic alkaline earth metal compound to a temperature in the range of about 260 F. to about 305 F. and adding water to said heated mixture in amount sufiicient to cover the reaction mass, whereby there is formed an alkaline earth metal naphthenate having an acid value lower than about 5.

8. The method of making calcium naphthenate which comprises heating a mixture of a naphthenic acid and mineral oil, said mixture containing about 335% by weight mineral oil, with a substantially stoichiometric amount of calcium hydroxide to a temperature in the range of about 260 F. to about 305 F., and maintaining water in contact with said heated mixture, whereby there is formed a calcium naphthenate having an acid number lower than about 5.

9. The method of making calcium naphthenate which comprises heating a mixture of a naphthenic acid, mineral oil, and calcium hydroxide to a temperature in the range of about 260 F. to about 305 F., adding hot water in an amount equal to about half the weight of said acid, mineral oil, and hydroxide, removing a portion of said Water from contact with said heated mixture before said water has boiled away, and repeating said addition and said removing steps until the acid number of said calcium naphthenate has fallen below 5.

References Cited in the file of this patent UNITED STATES PATENTS 1,720,821 Coleman July 16, 1929 2,003,640 Wunsch June 4, 1935 2,091,020 Shipp Aug. 24, 1937 2,131,938 Donker Oct. 4, 1938 2,200,711 Berry May 14, 1940 

1. THE METHOD OF MAKING AN ALKALINE EARTH METAL NAPHTHENATE WHICH COMPRISES HEATING A MIXTURE OF A NAPHTHENIC ACID AND AN INORGANIC ALKALINE EARTH METAL COMPOUND TO A TEMPERATURE IN THE RANGE OF ABOUT 260*F. TO ABOUT 305* F. IN CONTACT WITH WATER IN AMOUNT SUFFICIENT TO COVER THE REACTION MASS. 